IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)
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Seed Drill Discharge Rate Variation Due to Varietal Differences Using an Automated Calibration Test Rig
No full textIndia occupies about 12.40% of the total world wheat area, whereas it contributes 11.77 % in the total wheat production globally. The seed cum fertilizer drills are majorly used for sowing wheat crop in India and other parts of Asia. Farm equipment calibration is an important aspect to reduce seed wastage and implement precision farming practices. An automated seed drill calibration test rig was designed and developed to study the inter-varietal differences in the seed rate with respect to different operating speeds of the seed drill and active lengths of the fluted roller. The developed test rig is capable of measuring the seed rate variation at meter level accuracy. The inter-varietal variations, due to bulk density of seeds, can account up to a variation of 17% or 23.9 kg/ha under similar operating conditions. Also, the operating speed is having significant effect on seed rate variation only with other pertinent variables like
The effect of an N-heterocyclic compound on corrosion inhibition of J55 steel in sweet corrosive medium
No full textThe corrosion inhibition behavior of a naphthoxazinone derivative 1-phenyl-1,2-dihydronaphtho[1,2-e][1,3]oxazin-3-one (PNO) on J55 steel in 3.5 wt% NaCl solution saturated with carbon dioxide was evaluated using weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The surface morphology on the metal sample was analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The adsorption of PNO obeyed the Langmuir isotherm. The results of potentiodynamic polarization indicated that the PNO molecule behaved as a mixed type inhibitor by reducing both the anodic and the cathodic electrochemical reactions. The surface analysis showed that the metal surface is considerably smoother and with more uniform morphology in the presence of the inhibitor. DFT based quantum chemical calculations and molecular dynamic (MD) simulations supported the experimentally obtained results
Tribological behavior of dodecylamine functionalized graphene nanosheets dispersed engine oil nanolubricants
No full textThe present study investigates the tribological properties of nanolubricants dispersed with dodecylamine functionalized graphene (DAG) in commercial engine oil. Standard techniques were used to determine the morphology of the DAG and the worn surfaces. The tribological properties of the nanolubricants were measured using UMT-2 tribotester with an in-house attachment developed for measuring the friction of liquid lubricants. The nanolubricants were observed to reduce the coefficient of friction (COF) by a maximum ∼40% in comparison to base engine oil. Parameters including the concentration, load and sliding velocity were found to influence the variation of COF considerably. Characterization of the wear tracks by EDX and XPS suggests the formation of a tribo-film as the plausible mechanism which lowers the COF in case of the nanolubricants
Ultrafast, Highly Sensitive, and Selective Detection of p-Xylene at Room Temperature by Peptide-Hydrogel-Based Composite Material
No full textA peptide/carbon dot (CD) composite xerogel is used as a selective p-xylene VOC (volatile organic compound) sensor. The fiber formation by the peptide allows us to attain a semiconducting property, whereas the presence of the CD amplifies the sensitivity. The selective detection of p-xylene is achieved at a very low concentration (response ≈ 96% for 50 ppm) with an ultrafast response (630 ms) and recovery (540 ms). The sensor is also able to detect p-xylene within crude oil, proving its industrial application. In comparison with the available VOC sensors, this work stands out as a low-cost, sensitive, and selective room-temperature p-xylene sensor with ultrafast sensing ability
Inverse analysis and multi-objective optimization of coupling mechanism based laser forming process
No full textLaser forming of non-developable surfaces necessitates simultaneous bending and shrinkage of the sheet blank. This can be obtained by coupling mechanism based laser forming. However, soft computing based modeling of this process as well as different laser parameter sets under coupling mechanism giving different optimum combinations of simultaneous bending and shrinkage is rarely reported. In this work, experiments have been carried out following a design of experiments with considered suitable ranges of the input factors, i.e., laser power, travel speed and laser beam diameter activating coupling mechanism. Response surface models for the outputs namely bending and thickening (resulted due to shrinkage) were developed in terms of the considered inputs and parametric effects were analyzed. Finite element modeling was also carried out to analyze the deformation behavior. Multi-objective optimization of laser parameters for different combinations of maximum/minimum of bending and thickening of the sheet material undergoing coupling mechanism has been shown. Forward and inverse models of the process have been built with the help of a backpropagation neural network (BPNN) and genetic algorithm-based neural network (GANN) based on experimental data. Because of the ability of genetic algorithm (GA) to obtain global search, GANN models provide better estimation of the input parameters for inverse modeling or process synthesis compared to that by the BPNN model. Finally, several dome-shaped surfaces were built with constant line energy but different Fourier numbers and hence, different proportions of bending and shrinkage. This was to demonstrate the importance of simultaneous bending and thickening of the sheet (achievable only by coupling mechanism) to generate such non-developable surface with minimal distortion
An Improved Modulation Strategy for Fast Capacitor Voltage Balancing of Three-Level NPC Inverters
No full textThis paper presents an improved pulsewidth modulation strategy in conjunction with an optimal compensator for fast capacitor voltage balancing in three-level neutral-point-clamped (NPC) inverter. The voltage balancing compensator is designed in such a way that it produces
optimal unbalance compensation coefficient according to
the inherent limitations related to the variability range of modulating signals. It generates maximum compensating
neutral current for the full modulation depth extending into overmodulation region and throughout the entire range of load power factor angles, and thus improves the unbalance compensation ability for all the operating conditions of the inverter. The optimal compensation offset signal corresponding to each operating point is determined from the boundary limit of the auxiliary modulating signals. Particle swarm optimization is applied for such purpose. The performance of the proposed optimal compensator for different combinations of modulation index and load power factors are evaluated through extensive simulation study using Matlab/Simulink and validated in experimentation using a threelevel NPC inverter prototype with induction motor load. Finally, the voltage balancing performances of the proposed
compensator are compared with that available in literature to confirm the usefulness of the proposed concept
Evaluation of anti-corrosion performance of an expired semi synthetic antibiotic cefdinir for mild steel in 1 M HCl medium: An experimental and theoretical study
No full textIn view of severity of metallic corrosion in different corrosive media, application of corrosion inhibitor has been very promising to overcome this problem. However, numbers of corrosion inhibitors investigated earlier are not environmentally safe as well as costlier. To overcome these problems, researches are going on to develop efficient, environment friendly as well as cost effective corrosion inhibitor. In view of these facts, corrosion inhibition property of an expired anti-biotic, cefdinir (CDR) was investigated. This study includes anti-corrosion performance of CDR molecule against corrosion of mild steel (MS) in HCl medium. The results are summarized on the basis of weight loss, electrochemical, morphological and theoretical studies. The weight loss study infers that the rate of corrosion regularly decreased by the increasing the amount of CDR in acid solution. The cefdinir thus adsorbed on the MS surface and mitigate the corrosion rate. The adsorption of CDR on MS surface obeys Langmuir isotherm. The activation energy regularly increased by the presence of CDR and hence indicated that energy barrier for corrosion process to take place increased. The increased entropy of activation in presence of CDR assigned to entropy of solvent molecule. Potentiodynamic study infers that the CDR acts as mixed type of inhibitor. The value of Gibb’s free energy suggested the electrostatic as well as chemical interaction of CDR molecule with mild steel surface. The theoretical study (Density functional theory, Fukui indices and Molecular dynamics) justifies the experimental results appreciably
Selecting effective intrinsic mode functions of empirical mode decomposition and variational mode decomposition using dynamic time warping algorithm for rolling element bearing fault diagnosis
No full textEmpirical Mode Decomposition (EMD) and Variational Mode Decomposition (VMD) are data-driven self-adaptive signal processing methods to decompose a complex signal into different modes of separate spectral bands, in to a number of Intrinsic Mode Functions (IMFs). While the EMD extracts modes recursively and empirically, the VMD extracts modes non-recursively and concurrently. In this paper, both the EMD and the VMD have been applied to examine their efficacy in fault diagnosis of rolling element bearing. However, all the IMFs do not contain necessary information regarding fault characteristic signature of the bearing. In order to select the effective IMF, the Dynamic Time Warping (DTW) algorithm has been employed here, which gives a measurement of similarity index between two signals. Also, correlation analysis has been carried out to select the appropriate IMFs. Finally, out of the selected IMFs, bearing characteristic fault frequencies have been determined with the envelope spectrum
The evolution of foil bearing technology
No full textThis paper presents a state-of-the-art survey on the development of the foil bearing technology. Foil bearings represent a proven technology with many promising features. Nevertheless, there are a number of inherent challenges in their designs, analyses, and performance characteristics that must be taken into consideration for proper functionality and safe operation. To this end, complexities associated with geometrical configurations with the compressible flow, dynamic performance and stability associated with stiffness and damping, frictional characteristics associated with low- and high-speed operations, and thermoelastic instability leading to thermally-induced runaway are discussed in depth with particular attention to their progressive evolutions
Interspecies microbial nexus facilitated methanation of polysaccharidic wastes
No full textCompositional variations in organic wastes influence microbial abundancy and syntrophy during anaerobic digestion (AD), impacting the normal performance of digesters for methanation. Investigation of the microbial dynamics during AD following augmentation with polysaccharidic wastes (PW) revealed the association of effective digester performance and methane yields with the microbial nexus. Dominance of the acidogenic saccharolytic genera, Prevotella, Eubacterium, and Lachnoclostridium, enhanced the utilization of carbohydrates (54%) in PW-augmented digesters. Spearman’s rs correlation showed dynamic interspecies interactions among acetogenic syntrophs, and that of iron oxidizers/reducers with acetoclastic and hydrogenotrophic methanogens. Propionate oxidizers in Chloroflexi (i.e., Bellilinea, Levilinea, and Longilinea) exhibited positive associations with acetoclastic methanogens. Increase in the population of acetoclastic methanogens (Methanosaeta, 77% and Methanosarcina, 9%) accelerated the methanogenic activity of PW-augmented digesters by 7 times during the exponential phase, increasing the methane yield (75%) compared to the control. Thus, microbial syntrophy facilitated the effective methanation of PW during AD process